Factory-type apparatus for producing prestressed concrete products

Abstract

A factory for manufacturing concrete products, in particular prestressed concrete products, comprising a rotary supporting housing of a general cylindrical shape, having a horizontal axis of rotation and conveying moulds, for the concrete products, placed on its internal surface. The rotary housing comprises a circular carrier structure supported by means permitting the rotation of the said carrier, and a structure, resistant to longitudinal stresses, arranged in the interior of the carrier structure. The resistant structure comprises, on the one hand, longitudinal recesses adapted to receive sets of moulds, and, on the other hand, at one longitudinal end means for the attachment of reinforcement wires of the concrete products and, at its other longitudinal end, means for tensioning the reinforcement wires, such that the tensile stresses of these wires are taken up exclusively by the aforesaid resistant structure.

I claim: 
     
       1. A monoblock factory or installation for the manufacture of concrete products, in particular prestressed and/or reinforced concrete products, comprising a rotary supporting housing of a general cylindrical shape having a horizontal axis of rotation, a plurality of working stations mounted on a construction disposed in the interior of said housing, and a plurality of conveying moulds, for the concrete products, disposed on the internal surface of said housing so as to cause these moulds to pass in front of various of said working stations, the said working stations comprising a concrete-casting installation, a heat-treatment installation and a mould-stripping and manufactured products discharge installation, said factory being characterized in that the rotary housing comprises a rotatable circular carrier structure having a horizontal axis and supported by means permitting the rotation of the said carrier structure on its axis, means for rotating said carrier structure and means resistant to longitudinal stresses in a direction parallel to the axis of rotation of the carrier structure, said resistant means being disposed radially inwardly of the carrier structure toward the axis of rotation and being fixed to the carrier structure, and comprising elongate longitudinal extending members defining longitudinal recesses extending parallel to the axis of rotation of the carrier structure and provided around the entire internal periphery of the said carrier structure, the said recesses receiving sets of moulds for the products to be manufactured, the said resistant means comprising at one longitudinal end, means for the attachment of reinforcement wires of the concrete products and, at its other longitudinal end, means for tensioning the reinforcement wires, such that the tensile stresses of these wires are taken up exclusively by the aforesaid resistant means. 
     
     
       2. A factory according to claim 1, wherein said means permitting rotation of the carrier structure comprises rolling means and characterized in that the circular carrier structure comprises at both longitudinal ends an annular circular end ring adapted to run on said rolling means, being rigidly connected together by longitudinal tubular elements, the resistant means projecting on either side of the aforesaid carrier structure. 
     
     
       3. A factory according to claim 1, characterized in that said elongate members comprise longitudinal girders extending parallel to the axis of rotation of the carrier structure, arranged radially inwardly of said carrier structure and fixed thereto, the said longitudinal girders being regularly spaced over a complete circumference, so as to form between them the recesses for the moulds. 
     
     
       4. A factory according to claim 3, characterised in that the longitudinal girders of the resistant structure have a cross-section of substantially isosceles trapezoid form, the small base of which is turned towards the axis of rotation of the rotary housing. 
     
     
       5. A factory according to claim 4, characterized in that the walls opposite of two successive longitudinal girders extend radially such that the moulds may be inserted in or removed from the space included between the girders by radial displacement. 
     
     
       6. A factory according to claim 1, wherein said elongate members comprise at least two longitudinal girders arranged one after the other, between which are placed casting means, arranged after one another, such that a number of concrete products are aligned one behind the other between the girders, and the reinforcement wires extend along the entire length of the longitudinal girders so as to pass through several successive moulds. 
     
     
       7. A factory according to claim 6, characterized in that the concrete casting means comprises: a shell formed by the assembly of a plurality of unit moulds placed side by side transversely, each unit mould permitting fabrication of the product,   a framework on which the shell is fixed, the said framework being carried by the longitudinal girders,   and a cover which, in the operative position thereof, rests on the surface of the concrete contained in the moulds forming said shell and as to be separated from the shell.   
     
     
       8. A factory according to claim 6, characterised in that the casting means are mounted between the longitudinal girders for permitting sliding in the londitudinal direction of the said girders. 
     
     
       9. A factory according to claim 6 characterized in that said tensioning means comprise a device permitting the tension applied to the reinforcement wires to be gradually reduced. 
     
     
       10. A factory according to claim 9, characterized in that the device permitting gradual reduction of the tension comprises stop means at one end of the longitudinal girders at which end the application of tension is effected, and means for the continuous adjustment of the longitudinal position of the stop means with respect to the longitudinal end of the girders. 
     
     
       11. A factory according to claim 10, characterized in that the means for the continuous adjustment of the longitudinal position of the stop means comprise a screw fixed to the end of the girders and a nut mounted on the said screw, and acting as retention member for a stop of the stop means when a pull is exerted on the reinforcement wires. 
     
     
       12. A factory according to claim 10, characterized in that the means for the continuous adjustment of the longitudinal position of the stop means comprises a device having wedges having surfaces with reciprocal slopes, the said wedges being placed between a pulling head integral with the stop means and a fixed stop formed by a longitudinal end of the girders, the whole being such that the movement of the pulling head in a direction perpendicular to the reinforcements is accompanied, owing to the arrangement of the wedges by a gradual reduction in the distance between the stop means of the pulling head and the longitudinal end of the girders. 
     
     
       13. A factory according to claim 12, further comprising push means operatively associated with said pulling head for assisting in controlling the movement of the pulling head in a direction perpendicular to the reinforcement wires during stripping of concrete products. 
     
     
       14. A factory according to claim 12, further comprising means, disposed at the end of the girders remote from the pulling head, for the attachment of the ends of the reinforcement wires bearing against the end of the girders by means of a device having wedges defining stop surfaces having reciprocal slopes. 
     
     
       15. A factory according to claim 1 wherein said concrete-casting installation comprises covers, adapted to be separated from the moulds, for covering the moulds, and further comprises means for removing the covers from the moulds when the concrete has set sufficiently, and for returning the said covers to the moulds at the end of the operation of pouring the concrete. 
     
     
       16. A factory according to claim 15, wherein said elongate members comprise longitudinal girders and wherein the moulds are arranged in rows one after the other between pairs of said longitudinal girders, the covers of one row being carried by a longitudinal supporting element, and means for holding the supporting element are provided at each end thereof. 
     
     
       17. A factory according to claim 16, wherein the ends of said supporting element include rollers and the means for holding the supporting element comprise a circular arc rail adapted to bear against the rollers of said supporting element, and the means for removing the covers comprise, at the upper end of the rail, a pivotal element for assisting the movement of the supporting element and covers to the operative, mould covering positions thereof. 
     
     
       18. A factory according to claim 1 wherein said concrete-casting installation comprises means for pouring concrete to said moulds comprising a transport truck adapted to receive the concrete to be poured and to move along a row of said moulds, and an intermediate feed truck provided between a principal bin containing the concrete and the transport truck, the said feed truck being adapted to slide longitudinally, following the direction of the sets of moulds, and to be filled with concrete from the bin containing the concrete, when the transport truck is moved for filling the moulds, the said feed truck collecting an amount of concrete corresponding to that necessary for filling a mould, the said feed truck having a bottom adapted to be opened widely for ensuring a rapid transfer of the concrete contained in the feed truck to the transport truck when the feed truck is above the transport truck. 
     
     
       19. A factory according to claim 18, characterised in that said concrete-casting installation comprises a buffer bin arranged between the principal bin and the feed truck. 
     
     
       20. A factory according to claim 18, characterised in that the feed truck and transport truck comprise side walls forming a continuous contour such that the mix collected by the feed truck corresponds to that necessary for filling the moulds according to the type of products to be manufactured, the said walls being placed on a horizontal bottom comprising two shutters adapted to slide horizontally for opening or closing by the action of a hydraulic jack. 
     
     
       21. A factory according to claim 18 further characterized in that said concrete-casting installation comprises guide means and a smoothing device adapted to be moved on said guide means, the said smoothing device being situated in an inoperative position, on the outside of the axial direction of the set of moulds arranged one after the other, the said smoothing device comprising a bin containing concrete, for ensuring complete filling of the moulds, and a vibrating head adapted to move over the upper surface of the moulds, the said vibrating head comprising a scraping element and being supported by a vertical lifting device enabling it to be placed at an appropriate level for crossing obstacles. 
     
     
       22. A factory according to claim 18, further comprising mould-vibrating means formed of at least one horizontal girder for each set of moulds extending perpendicular to the vertical plane passing through the longitudinal axis of the set of moulds and supported by lifting means futher, means operatively associated with said horizontal girder being provided for imparting to the said horizontal girder a vibratory motion, the lifting means being adapted to bring the horizontal girder into contact with the set of moulds while the set of moulds is being filled with concrete. 
     
     
       23. A factory according to claim 22, futher comprising means operatively associated with said mould-vibrating means for attaching the mould-vibrating means to the moulds. 
     
     
       24. A factory according to claim 23, characterised in that the attaching means comprise clamping arms pivoted in the vicinity of their upper ends to a support, while their lower ends are connected by a jack. 
     
     
       25. A factory according to claim 1, wherein the heat-treatment installation comprises a fixed heat screen situated outside the housing and resting on the latter by rotary rollers, the said heat screen comprising a metal framework and a heat screen formed by a sheet of thermally insulating material, a second heat screen being provided in the interior of the rotary housing. 
     
     
       26. A factory according to claim 25, characterised in that a heating means is arranged between the external heat screen and the moulds for sending a heat flow towards the moulds passing by them. 
     
     
       27. A factory according to claim 26, characterised in that the heating means comprise infra-red radiators. 
     
     
       28. A factory according to claim 1 wherein said mould-stripping installation comprises a head carried by a jointed tube and comprising recesses adapted to receive the cast products, means for controlling a movement in translation and rotation of the head, the means for stripping cast products from the moulds. 
     
     
       29. A factory according to claim 28, wherein said stripping means includes push means comprising push fingers adapted to exert a thrust against the cast products for loosening the said products with respect to the moulds. 
     
     
       30. A factory according to claim 1 further comprising an installation mounted on said construction for feeding said reinforcement wires that comprises a feed device, for feeding said reinforcement wires, comprising a tubular element around which are arranged at regular intervals crowns provided with radial grooves opening into the external periphery of the crowns, the said grooves being adapted to receive the reinforcement wires the tubular element being given a movement of rotation such that, for a predetermined inclination of the groove containing a reinforcement wire, the latter escapes from the said groove by gravity. 
     
     
       31. A factory according to claim 30, further comprising a split tube arranged above the feed device for the reinforcement wires, the said split tube comprising a longitudinal slot and being adapted to turn on its axis so that the longitudinal slot occupies the lower part of the said tube when a cut reinforcement wire is intended to drop into the feed device.